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The following attributes must be set in a <condition> element definition:

Attribute

Usage

type

The type of the condition. For built-in types, this is the lowercase portion of the condition class name without condition appended (variable,packselection,java, ...). Custom condition types should be referenced by the full qualified class name, e.g. de.dr.rules.MyCoolCondition.

id

The id of the condition. This will be used to refer to this conditions in other elements

<condition> - Nested Elements

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From IzPack 3.11 on, you don't have to define compound conditions because you can use a simple expression language. The language supports the following operators:

+

an operator for the And Condition

|

an operator for the Or Condition

^

an operator for the Xor Condition

!

an operator for the Not Condition

These simple expressions DO NOT follow the usual boolean logic with precedence rules. Instead, they are evaluated left to right in a simple way.

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Code Block
!(conditionA && (conditionB && !(conditionC)))

 


Example:

Code Block
languagexml
titleinstall.xml
<dynamicvariables>
    <variable name="db.instance" value="MSSQLSERVER" checkonce="true" condition="useMssql+mssqlInstanceSelected+!haveDatabaseURL" />
</dynamicvariables>

 


Anchor
Complex expression language
Complex expression language
Complex expression language

Beginning with IzPack 5.0, there is also the possibility to use a more complex expression language which evaluates based on boolean precedence rules, which is also reflected in the following table. The higher an operator is, the higher is its precedence.

^

an operator for the Xor Conditon

&&

an operator for the And Condition

||

an operator for the Or Condition

!

an operator for the Not Condition

 


Example:

Code Block
@!conditionA&&conditionB&&!conditionC

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In order to use the complex expression language the expression must start with a '@' character. 


Example:

Code Block
languagexml
titleinstall.xml
<dynamicvariables>
    <variable name="db.instance" value="MSSQLSERVER" checkonce="true" condition="@useMssql && !haveDatabaseURL && mssqlInstanceSelected" />
</dynamicvariables>